It seems that I am going to have to replace most if not all of my jets on this tub as they are all breaking and falling apart and out of the tub. Is there any way to know what replacement parts to order from someone other than Icon? I would like to buy them aftermarkey to save money. Are jets like most tub parts and most parts are made by a handfull of companies and are then used in each brand of tub?
Hope this makes sense. I am thinking they look a lot like waterworks jets that I have seen on many websites.
Thank you!

Yes, highly likely that your spa jets will also be fitted to a number of other brands.

I'd send a faulty one to a jet supplier to compare.

There's a chance you'll find a part number on the insert itself. If not, take some pics with a measuring tape for scale and send it to a few online vendors. They'll be able to find it for you.